Soon after gunmen stormed a Kenyan shopping mall on Saturday, killing dozens in a spray of bullets and grenades, triumphant tweets swept the Internet.

"The Mujahideen entered #Westgate Mall today at around noon and are still inside the mall, fighting the #Kenyan Kuffar inside their own turf," cheered the Twitter account of al Shabab, al Qaida’s affiliate in Somalia. "The Mujahideen inside the mall confirmed to @HSM_Press that they killed over 100 Kenyan kuffar & battle is ongoing."

Hours later, the account disappeared. For the third time this year, Twitter tried to kick al Shabab off its social media platform.

Within hours, a new account popped up once again, tweeting mocking jibes at Kenyans as if it had never stopped. Then it too went silent.

As the horror of the assault on Nairobi’s Westgate mall spun unresolved through a second day Sunday, with the death toll rising and uncertainty surrounding what was taking place at the multi-story complex, the Internet became the only way to learn the motivations of the attackers – amid fierce debate over whether terrorists should have their own platform.

The Saturday attack on the upscale Israeli-owned shopping mall – a popular destination for wealthy Kenyans and Nairobi’s large expatriate community – was the deadliest terror attack since August 1998, when the U.S. Embassy here was bombed, killing more than 200.

Kenyan officials on Sunday issued revised accounts of the mayhem: 59 people dead, more than 175 wounded. Security forces were battling to claw control of the shopping center from the attackers who remained inside. More than 1,000 shoppers had been rescued, officials said, but an unknown number remain trapped inside.

There was little said publicly about the perpetrators of the attack, except for what emerged on Twitter.

In Afghanistan and Pakistan, al Qaida spokesmen regularly communicate directly with journalists, often by phone. Shabab, too, has an official spokesman – but he is in Somalia, is rarely reachable, and communicates mostly to only a trusted ring of media contacts.

So, when news broke of the attack on Saturday, practically every journalist in East Africa turned immediately to the unsavory sarcasm flowing out of @HSM_Press, Shabab’s latest Twitter account.

So, too, did the Kenyan government.

"The al Shabab terror group has claimed responsibility for this cowardly act of terror on social media. However, investigations are underway to conclusively establish those responsible for this mayhem," President Uhuru Kenyatta of Kenya said in a televised statement Sunday evening.

The sheer scale of the damage inflicted by the armed attack began to sink in on Sunday, as the number of dead continued to climb and the bloody standoff inside the mall spilled into a second night, with the chance of even more casualties to come.

President Kenyatta told the nation his nephew and nephew’s fiance were among the dead.

The U.S. State Department said it knew of no Americans who’d died in the attack, but that five had been wounded. It said in addition to Kenya, the dead came from Australia, Great Britain, Canada, France, Ghana and Somalia.

Kenyatta said that the assailants, estimated to number 10 to 15 and possibly including women, had been cornered in one location at the mall. He declined to give many other details, asking the nation to let "professionals" do their work.

Helicopters whirred overhead as Kenyan security forces expanded their cordon around the mall, deploying hundreds of troops in the streets surrounding the complex. As night fell, more troops arrived and took up additional positions around the building.

Kenyan authorities announced they had re-taken control of the building’s closed circuit television room, a step toward further securing most of the mall. Survivors have told hair-raising tales of hiding in bathroom stalls and storage rooms as the gunmen executed scores of others nearby.

Al Shabab, through its Twitter account, said the attack was retribution for the Kenyan military’s offensive into Shabab strongholds in southern Somalia that began in 2011 after a string of cross-border kidnappings.

As anger swept through Kenya at the scale of the attack, Kenyan Twitter users began demanding that Shabab again have its account cancelled.

"The danger of course is that they get a following among young gullible people," said Rashid Abdi, an independent Somali analyst.

But from an intelligence perspective, said Abdi, "allowing these people some kind of forum where they can make claims is important."

Intelligence services closely monitor flagged terror accounts to help map out other networks of online supporters.

"It’s hard to take one side or the other," said Abdi.

In the end, the organization’s clear delight in brashly boasting of past and future violence appears to force Twitter’s hand toward the delete button.

In January, the group’s account was removed after it tweeted a picture of a dead French soldier and threatened to execute Kenyan captives. Earlier this month, the group’s account was deleted after it jeeringly vowed to take the life of the Somali president.

The group clearly has no plans to give up its tweeting habit anytime soon.

"Kenyans will not appreciate the gravity of the situation without seeing, feeling and experiencing death in all its ghoulish detail," tweeted a new account, @HSM_PressOffice, claiming to be Shabab.